The error entries and tests for PRI-CDR also apply to CDR-LNK and SEC-CDR.

The CDR feature records detailed call information about every incoming and outgoing call on specified trunk groups and sends this information to a CDR output device. The two physical links can be administered for connecting external CDR output devices to the system. They are identified as the primary CDR (PRI-CDR) link and the secondary CDR (SEC-CDR) link. The CDR device connects to the system via a data module, such as, PDM, MPDM, DTDM connected to a port on PROCR. External CDR output devices include:

• 94A Local Storage Unit (LSU)
• TELESEER CDR Unit
• Call Accounting System (CAS)
• Call Detail Recording Unit (CDRU)
• Printer
• Host computer
• Personal computer (PC)
• Customer-provided equipment

CDR link maintenance provides a strategy for maintaining the link between the system and an external CDR output device. The strategy includes a set of tests for periodic diagnosis, detection of errors during normal operation, actions for troubleshooting, and raising alarms for serious problems. CDR link maintenance uses a try-and-wait mechanism for maintaining the CDR link. If the CDR link is torn down due to an error, CDR link maintenance tries to bring the CDR link up. If the Link Setup fails, CDR link maintenance will wait for 30 seconds before the next retry. If the number of retries reaches a threshold of two, a minor alarm is raised for service attention.

CDR Link Maintenance does not cover the maintenance of the elements composing the CDR physical link:

• External CDR output device

If CDR link maintenance cannot restore the CDR link, the maintenance tests of these individual components of the CDR link must be executed to diagnose faults.